Identification of an individual by electronic means for biometric identification has developed substantially owing to progress in information technology and microelectronics, achieving a high degree of rapidity and reliability.
In the methods commonly used, identification is a result of digital fingerprint recognition, but may also be the result of facial recognition, vocal recognition, morphological recognition or indeed iris recognition.
It is known to perform biometric fingerprint acquisition using an optical capture device.
The operating principle of this technology is well known. Acquisition involves capturing a partial or complete area of the individual's dermatoglyphic structure. This area is usually restricted to one or several of the individuals' distal phalanges.
Commonly, the capture device comprises an optical sensor combined with a means of illumination providing controlled exposure to light of said phalanges. The exposure to light is controlled in order to increase the contrast of the papillary lines and hence increases identification accuracy.
The quantity of light may vary significantly depending on ambient lighting, but may also vary according to the physiological status of the finger (for example, depending on whether the finger is dry or moist). The lighting level needs to be adapted to these conditions in order to increase acquisition quality.
Furthermore, it is known to use light radiation of different wavelengths in order to facilitate fraud detection.